SOUTH SAN FRANCISCO, CA--(Marketwired - May 28, 2013) - Portola Pharmaceuticals, Inc. (NASDAQ: PTLA) announced today the closing of its initial public offering of 9,686,171 shares of its common stock at a price to the public of $14.50 per share. All of the 9,686,171 shares are being offered by Portola and include 1,263,413 shares issued pursuant to the over-allotment option granted to the underwriters, which was exercised in full.

Morgan Stanley and Credit Suisse acted as the joint book-running managers for the offering. Cowen and Company, William Blair and Sanford C. Bernstein acted as co-managers. Copies of the prospectus relating to this offering may be obtained from the offices of Morgan Stanley & Co. LLC, Attention: Prospectus Department, 180 Varick Street, 2nd Floor, New York, New York 10014, or by email at prospectus@morganstanley.com or Credit Suisse Securities (USA) LLC, Attention: Prospectus Department, One Madison Avenue, New York, NY 10010, by email at newyork.prospectus@credit-suisse.com or by toll-free call to (800) 221-1037.

A registration statement relating to these securities has been filed with, and was declared effective by, the Securities and Exchange Commission on May 21, 2013. This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Portola Pharmaceuticals, Inc.

Portola is a biopharmaceutical company focused on the development and commercialization of novel therapeutics in the areas of thrombosis, other hematologic disorders and inflammation for patients who currently have limited or no approved treatment options. Portola's current development-stage portfolio consists of three compounds discovered through its internal research efforts and one discovered by Portola scientists during their time at a prior company.

Portola's two lead programs address significant unmet medical needs in the area of thrombosis, or blood clots. Portola's lead compound, betrixaban, is a novel oral once-daily inhibitor of Factor Xa in Phase 3 development for extended duration prophylaxis, or preventive treatment, of a form of thrombosis known as venous thromboembolism, or VTE, in acute medically ill patients. Currently, there is no anticoagulant approved for extended duration VTE prophylaxis in this population.

Portola's second lead development candidate, PRT4445, is a recombinant protein designed to reverse the anticoagulant activity in patients treated with a Factor Xa inhibitor who suffer an uncontrolled bleeding episode or undergo emergency surgery. Portola has entered into a collaboration agreement with Bristol-Myers Squibb Company and Pfizer Inc. and a collaboration agreement with Bayer Pharma AG and Janssen Pharmaceuticals, Inc. to study PRT4445 with Eliquis® and XARELTO®, respectively, in Portola's Phase 2 studies. Portola retains full, worldwide commercial rights with respect to PRT4445.

Portola's third product candidate, PRT2070, is an orally available kinase inhibitor being developed for hematologic, or blood, cancers and inflammatory disorders. PRT2070 inhibits spleen tyrosine kinase, or Syk, and janus kinases, or JAK, enzymes that regulate important signaling pathways. Subject to regulatory approval, Portola plans to initiate a Phase 1/2 clinical study of PRT2070 in 2013 in patients with B-cell hematologic cancers who have failed or relapsed on existing marketed therapies or products in development, including patients with identified mutations. Portola's fourth program, PRT2607 and other highly selective Syk inhibitors, is partnered with Biogen Idec Inc.